The present invention relates to machines for printing and cutting blanks of corrugated paperboard for assembly into boxes or other structures and, more particularly, to a print-cutter machine with a modular print section having a plurality of ink applicators and a precision adjustment mechanism for the ink applicators.
Corrugated paperboard boxes are commonly used by merchants and manufacturers for shipping and/or storing a wide range of products, from produce to electronics. These boxes are typically made from corrugated paperboard blanks that are cut and/or scored to permit folding into the shape of a box. Additionally, the blanks are usually printed with text and/or graphics relating to product identification, specifications, instructions for handling, storing, or assembly, and so forth. In order to efficiently print and cut a quantity of blanks, a printer-cutter machine is commonly utilized.
Conventional printer-cutter machines have feed rolls for drawing a blank from a stack of blanks and feeding it between an impression roll and a print roll. The print roll has a print plate with a reverse image of the desired text and/or graphics formed thereon. The position of the printing on the blank is set by the registration of the print roll, that is, by the position of a timing mark on the print roll relative to the leading edge of the blanks. An ink applicator with an ink chamber mechanism and an engraved roll applies ink to the print plate, and the ink-laden print plate prints the text and/or graphics onto the blank. Traditionally, rotary cylinder-type printing machines have employed only a single ink applicator for each print roll.
Subsequently, transfer rolls feed the blank between an anvil roll and a cutting roll with one or more cutting dies with edges extending from it for cutting the blank as desired. The feed rolls, impression roll, print roll, engraved roll, transfer rolls, anvil roll, and cutting roll are interconnected by gears or belts that are driven by a rotary power source such as an electric motor.
After processing a batch of blanks for one application, the printer-cutter machine must be reconfigured for the next printing and cutting job. With regards to cutting, normally only the cutting dies on the cutting roll need to be replaced when making different sized boxes. In that case, the cutting roll is reconfigured with different cutting dies and with a different registration in order to produce cuts of the desired length at the desired locations on the blanks. With regards to printing, there are three components of the machine that are commonly replaced or adjusted between jobs: the print plate, the print roll registration, and the ink rolls of the ink applicators.
The print plate is usually replaced in order to change the particular text and/or graphics printed onto the blanks. This involves removing the print plate from the print roll and installing a new print plate with the new text and/or graphics. Normally, this is a relatively quick and easy task.
The registration of the print roll is changed in order to print a different text and/or graphic at a different location on the blanks, when making different sized boxes. This involves changing the position of the print roll so that the timing mark is adjusted relative to the leading edge of the blanks. This is typically not an overly burdensome task but does take some time to accomplish.
Additionally, the ink rolls of the ink applicators are often reconfigured or replaced to change the color and/or grade of the printing. For some applications, particularly those including graphics, vignettes, process, and fine text and line printing (e.g. bar codes), the merchant or manufacturer wants high quality and resolution printing on the boxes. For this generally xe2x80x9cfinexe2x80x9d grade printing, a relatively thin layer of ink is applied to the print plate. Therefore, an engraved roll is used that has a textured surface with an ink-carrying matrix of a relatively large number of shallow cells. In other applications, heavy lines and solid figures are desired for ease of viewing the printing. For this generally xe2x80x9ccoarsexe2x80x9d grade printing, a relatively thick layer of ink is applied to the print plate. Therefore, an engraved roll is used that has a textured surface with a matrix of a smaller number of deeper cells. Also, the printing grade can be influenced by the geometry of the cell matrix, so the engraved roll can be selected with a matrix having any of a variety of cell geometries, including hex patterns, diamond patterns, or other regular patterns or irregular textured matrices.
Thus, for each particular printing application with a desired print grade, an engraved roll with the appropriate surface matrix is installed in the machine. The appropriate surface matrix is a function of the line screen (number of cells per inch or other length), cell volume (in billions of cubic microns xe2x80x9cBCMxe2x80x9d or another volume unit), and cell geometry. Often, a combination of fine, coarse, or another grade of printing is provided in each print job.
In order to change out an engraved roll, the machine must be stopped and partially disassembled for access to the engraved roll. Then the engraved roll is removed and the engraved roll for the next print job installed. Finally, the machine must be reassembled and the machine restarted. This process is time consuming and typically is performed by highly trained maintenance personnel, not the machine operator.
Additionally, in order to change the ink color, the machines are typically provided with liquid lines and pumps for supplying water or another liquid to wash the ink chamber components prior to supplying a different color ink. Because only one ink applicator is provided, it cannot be used while the single ink chamber is being cleaned, so this is often done while the machine is idle between print jobs.
Thus, conventional printer-cutter machines suffer from a number of deficiencies when reconfiguring them between printing and cutting jobs:
(a) To change the print grade, the engraved roll must be changed out. For example, it is common to remove a coarse roll and install a fine roll, or vice versa, between print jobs, sometimes in order to manufacture a single batch of boxes. To access the engraved roll for change-out, the machine must be partially disassembled, the engraved roll replaced, and the machine reassembled, a process which takes a considerable amount of time.
(b) To adjust the machine for a different color printing, the engraved roll and ink chamber mechanism must be cleaned, then the different color ink supplied, sometimes adding significantly to downtime between print jobs.
(c) To change the position of the printing on the blank, the registration of the print roll must be adjusted.
The result is that between printing-cutting jobs, the printer-cutter machine operator typically stands by while maintenance personnel disassemble and reassemble the machine. With the machine disassembled, the operators replace or clean the engraved roll, clean and refill the ink chamber, and/or make any other needed adjustments. These are time-consuming, manual tasks that cannot be performed while the printer-cutter machine is in operation (without interfering with the job in progress). Therefore, the machine is often idle for a significant period of time between printing and cutting jobs while maintenance personnel and the operators make the changes necessary for the next job. For many printer-cutter machines, this downtime is on the order of about 8-10 minutes or so (for only cleaning the ink chamber) or about on hour or so (for changing out the ink roll). This downtime significantly reduces the machines effective efficiency and profitability. Additionally, having qualified personnel available to perform these involved tasks adds to labor costs.
Accordingly, there is a need for a printer-cutter machine for corrugated paperboard blanks that can be quickly and easily configured for printing the desired grades and colors at desired locations on the blanks, with little or no resulting downtime between printing and cutting jobs. Furthermore, there is a need for a machine that provides a wide variety of options in grades and colors of printing so that the engraved roll rarely if ever needs to be changed-out.
The present invention meets the aforementioned needs by providing a printer-cutter machine that can be refitted for a subsequent printing-cutting job with a downtime typically on the order of about 1-2 minutes or less. The machine has two (or more) ink applicators for each print roll, with each ink applicator having an engraved roll and an ink chamber mechanism. Each print roll can be provided with the associated ink applicators each having engraved rolls with different textured surface matrices and with ink chambers having different colors of ink, so that the ink applicators need to be refitted less often.
For example, one ink applicator can be fitted with an engraved roll having a fine textured surface for high quality graphics printing and the other ink applicator can be fitted with a coarse textured engraved roll for large, bold printing. As a further example, one of the ink applicators can supply black ink to the print roll and another ink applicator can supply red ink. Additional print rolls and ink applicators can be provided, for example, four print rolls each having two ink applicators, thereby providing eight colors of ink available for printing. The invention thus provides the advantage of a wide variety of readily available printing options, both in print quality and color, so that the ink applicators rarely if ever need to be refitted with a different engraved roll or color of ink.
Furthermore, because the machine has two ink applicators for each print roll, one of the ink chambers can be cleaned and refilled with a different color ink while the other ink chamber is in use. This provides the advantage of retracting and refitting one of the ink applicators for a different color of ink for the next print job while the machine is in operation, instead of between jobs with the machine idle.
Additional features of the invention provide the advantage of more efficiently and precisely adjusting the position of the multiple ink applicators, because each ink applicator is now moved between an engaged xe2x80x9cin usexe2x80x9d position and a retracted xe2x80x9cout of usexe2x80x9d position. In order to quickly and easily move the ink applicators, each ink applicator can be provided with an applicator adjustment mechanism and an incremental actuator for selectively operating the applicator adjustment mechanism in increments or steps. Thus, by actuating the actuator, the corresponding ink applicator can be quickly and easily moved toward and into a precise position of contacting engagement with the print roll, or retracted away from and out of contacting engagement with the print roll, independent of the other ink applicator. Also, the ink wells may have pivotal mountings so that when the ink applicators are retracted, the ink wells can be easily swiveled to the side for providing access for quick and easy cleaning and maintenance of the ink wells.
Additionally, the machine can be provided in a modular arrangement with a modular feed section, one or more modular print sections, and a modular cutter section, each separably coupled together. Any number of modular print sections can be provided, for example, four of the print sections can be operatively connected together in series with the feed section and the cutter section. The print sections and the feed section and/or cutter section are mounted so that the print sections can be rolled or otherwise moved apart from each other after they are decoupled. This provides the advantage of easy access to the ink applicators and other components for maintenance, and the ability to add, remove, or retrofit entire print sections as may be desired.
Moreover, the present machine includes a print registration adjustment mechanism that allows for efficiently adjusting the registration of the print roll. When the print roll becomes out of registration or before printing a batch of blanks having a different size, a registration adjustment gearmotor can be actuated to selectively drive a differential gear-set and adjust the position of the timing mark on the print roll relative to the leading edge of the blanks, independent of the main drive for the machine. The result is that the print registration can be easily monitored and adjusted, so that the printing is always applied at the desired location on the blank.
Generally described, the invention is a machine for operating on blanks, for example, for performing printing and cutting operations on corrugated paperboard blanks for assembly into boxes. In this configuration, the machine has a feed mechanism, a print mechanism, a cutter mechanism, and a rotary main drive. The feed mechanism has two rotary feed rolls that draw the blanks from a stack of blanks into the machine and transport the blanks in series through the machine.
The print mechanism has a rotary impression roll, a rotary print roll, and at least one ink applicator. The impression roll and the print roll are positioned proximate to each other so that the space between them provides a nip for receiving the blanks in series. Any of a variety of print plates can be mounted onto the print roll, with each print plate having a reverse image of the desired text and/or graphics. Each ink applicator has an ink chamber mechanism and a rotary engraved roll, with the ink chamber mechanism supplying ink to the engraved roll which in turn applies the ink to the print plate. The ink-laden print plate then prints the text and/or graphics onto the blank passing through the nip.
A vacuum transfer mechanism having rotary transfer rollers advances the printed blanks to the cutter mechanism. The cutter mechanism has a rotary anvil roll and a rotary cutting roll with cutting blades attached to it for cutting the blanks as desired, for example, to form flaps for folding into a box.
The main drive rotationally drives the feed mechanism, the print mechanism, and the cutter mechanism. Accordingly, the main drive has a rotary power source such as an electric motor that is operatively connected to one or more of the feed rolls, which is operatively connected to a rotary transmission shaft, which is operatively connected to the impression roll, the print roll, the engraved rolls, transfer rolls, the anvil roll, and the cutter roll.
According to one aspect of the invention, the machine can have two (or more) ink applicators for each print roll. Additional ink applicators can be provided for each print roll as may be desired in a given situation. Each of the engraved rolls can have a different surface texture, for example, one engraved roll for xe2x80x9cfinexe2x80x9d grade printing might have a textured surface with an ink-carrying matrix of a relatively large number of shallow cells. Another engraved roll for xe2x80x9ccoarsexe2x80x9d grade printing might have a surface matrix of a smaller number of deeper cells. Of course, other engraved rolls with other textured surface matrices can be provided for producing the desired print grade.
Additionally, each ink chamber mechanism can have a support member, an ink well coupled to the support member for storing the ink, and two or more doctor blades extending from the ink well and contacting the engraved roll for applying the ink to the engraved roll. The ink wells can be coupled to the corresponding support member by a pivotal coupling, and the support members can be coupled to the corresponding engraved roll or other component so that the ink chamber mechanism and the engraved roll move together. Also, an ink chamber adjustment mechanism with at least one flexible tube can be provided for each ink chamber mechanism, for inflating and deflating the tube or tubes to move the ink chambers between an engaged position with the corresponding engraved roll and a retracted position.
Another aspect of the invention is an applicator adjustment mechanism for precisely moving each ink applicator, and actuators for quickly and easily operating each applicator adjustment mechanism. For example, each applicator adjustment mechanism can have two eccentric bearings for rotationally mounting the corresponding ink applicator to the machine, with the engraved roll axles off-center of the bearing axis so that rotating the eccentric bearings causes the ink applicator to move toward or away from the corresponding print roll independent of the other ink applicator. Also, each applicator adjustment mechanism can have an adjustment shaft with spur gears that drive spur gears on the eccentric bearings for rotating the eccentric bearings, a primary rotary actuator for rotating the adjustment shaft, a travel limiting mechanism for adjusting the rotational range limits of the primary actuator, and a secondary incremental actuator for incrementally adjusting the travel limiting mechanism. Thus, the ink applicators can be incrementally moved into the precise engaged position desired, or moved to the retracted position.
Alternatively, each applicator adjustment mechanism can have one or more pivot arms and actuators. The ink applicators are mounted on the pivot arms so that, upon operation of the actuator, the ink applicators pivot between the engaged and retracted positions. Additionally, the applicator adjustment mechanisms can include stops with eccentric cams for limiting and adjusting the pivotal travel of the pivot arms and ink applicators.
In a further aspect of the invention, the machine can be provided with a modular feed section, one or more modular print sections, and a modular cutter section. The modular feed section includes the feed mechanism and the feed drive supported by a feed section frame, the modular print sections each include one (or more) of the print mechanisms and one (or more) of the print drives supported by a print section frame, and the modular cutter section includes the cutter mechanism and the cutter drive supported by a cutter section frame. The feed drive transmission shaft is rotationally driven by the feed rolls, each print drive transmission shaft rotationally drives the corresponding print roll, impression roll, and engraved rolls, and the cutter drive transmission shaft rotationally drives the cutter roll and the anvil roll.
Any number of modular print sections can be provided, for example, four of the print sections can be operatively connected together in series with the feed section and the cutter section. The transmission shaft of each print section has an input end that can be separably coupled to an output end of the feed section transmission shaft (for the first print section) or to an output end of a preceding print section transmission shaft (for the second or third print section). Similarly, each print section transmission shaft of has an output end that can be separably coupled to an input end of the cutter section transmission shaft (for the fourth print section) or to an input end of another print section transmission shaft (for the second or third print section). The separable couplings can be provided by a spline-type coupling or another separable coupling permitting quick and easy disconnection of the transmission shafts. Additionally, the machine can have a track and roller bearings riding on the track and supporting the print section frames and the feed or cutter frame, so that the print sections can be rolled apart from each other after they are decoupled, for access to the ink applicators and other components for maintenance.
Accordingly, the machine can be employed in a method for retrofitting a pre-existing printer-cutter machine to provide increased printing options, where the pre-existing printer-cutter machine has a feed section, print section, and cutter section, each with a transmission shaft. In particular, the method comprises the steps of decoupling the transmission shaft of the pre-existing print section from the transmission shaft of the adjacent feed section or cutter section, and removing the pre-existing print section from adjacent the feed section and the cutter section. The method further comprises the steps of providing at least one print section having a rotary print roll, at least two ink applicators for each print roll, and a transmission shaft, wherein each ink applicator has an engraved roll and an ink chamber mechanism, disposing the print section adjacent the feed section or the cutter section, aligning the transmission shaft of the print section with the transmission shaft of the adjacent feed section or the transmission shaft of the adjacent cutter section and coupling the transmission shaft of the print section with the transmission shafts of the adjacent feed, print, and/or cutter section.
In still another aspect of the invention, each print drive can be connected to a registration adjustment mechanism. The registration adjustment mechanism has a differential gear-set that is operatively connected to a gearmotor and to the print roll, and that is selected so that actuation of the gearmotor changes the rate of rotation of the print roll. Thus, the print roll rate of rotation, which is controlled by the print drive, can be changed by actuation of the gearmotor.
In view of the foregoing, it will be appreciated that the present printer-cutter machine provides a substantial improvement over the prior art by producing a significant reduction in downtime between printing-cutting jobs. The specific techniques and structures employed by the invention to improve over the drawbacks of the prior systems and accomplish the advantages described above will become apparent from the following detailed description of the embodiments of the invention and the appended drawings and claims.